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Biomedical subjects

V V Radhakrishnan

Publications and source records attributed to V V Radhakrishnan.

At least 91 records · Page 5Linked to original sources
PubMed1993

Diagnostic utility of immunohistochemical techniques in intramedullary Schwann-cell tumours.

Histopathologic features in two intramedullary schwann-cell tumours, closely resembled with those of fibrillary astrocytoma and could not be differentiated from each other by the conventional histochemical stains. However application of tumour markers-Glial fibrillary acidic protein (GFAP) and S-100 protein were found to be useful in differentiating these two tumours and thus helped in making an accurate histopathological diagnosis in these two patients.

Astrocytoma↗
PubMed1992

Histopathological evaluation of polymethyl methacrylate as an embolic agent.

Polymethyl methacrylate (PMMA) microspheres were used as an embolic agent to reduce the vascularity in eight patients with intracranial vascular tumours. Post embolization angiograms showed 30-60% reduction in the vascularity of the tumours. No patient developed any neurological complications in the immediate post-embolization period. These eight patients subsequently underwent surgery for the removal of their tumours. During surgery there was minimal blood loss and a good plane of cleavage was obtained between the tumour and the adjacent brain. The surgical specimens were examined histopathologically for the effects of PMMA. PMMA microspheres, in contrast to other cyanoacrylates--isobutyl-2-cyanoacrylate (IBCA)--did not elicit either inflammatory reaction or mural angionecrosis within the wall of the embolised vessels. The histopathological studies suggest that PMMA microspheres are an inert material and can be used as an adjunct in the management of intracranial vascular tumours.

Adult↗
PubMed1992

Diagnostic significance of circulating immune complexes in patients with pulmonary tuberculosis.

A polyethylene glycol (PEG) precipitation method was used to examine sera of patients with active pulmonary tuberculosis (PT), leprosy and non-tuberculous pulmonary diseases and of healthy control subjects for immune complexes (ICs). Mycobacterium tuberculosis antigen 5 was detected in the ICs in 80% of patients with PT by the indirect (sandwich) enzyme-linked immunosorbent assay (ELISA). Detection of mycobacterial antigen in ICs has diagnostic potential as an adjunct in the laboratory diagnosis of PT, particularly when repeated bacteriological investigations for M. tuberculosis in clinical specimens are negative. Levels of ICs tend to decrease with the duration of anti-tuberculosis chemotherapy and their detection can also be used to assess the clinical response to therapy in patients with PT.

Antibodies, Bacterial↗
PubMed1992

Intradural spinal cavernomas.

Intradural cavernomas are rare vascular lesions of the spinal cord. Four cases of histologically verified cavernomas of the cord are reported, of which two were extramedullary and two were intramedullary in location. Progressive neurological deficit was the presenting feature in three cases while one patient had a rapid evolution of neurological deficits and was found at surgery to have had bled from the extramedullary lesion. All the patients were subjected to surgery and total excision of the cavernomas was carried out in each case. While two patients improved after surgery the other two remained static. The available literature on spinal cord cavernomas is reviewed.

Adult↗
PubMed1992

Evaluation of purified protein derivative in the laboratory diagnosis of tuberculous meningitis.

An enzyme-linked immunosorbent assay (ELISA) was standardised for the quantitation of IgG antibody in cerebrospinal fluid (CSF) specimens of patients with tuberculous meningitis (TBM). Purified protein derivative (PPD1) from H37Ra M tuberculosis was used as the antigen in the assay. The sensitivity of the ELISA with this antigen was evaluated in the CSF of 10 culture positive and 40 culture negative patients with TBM. The specificity of the assay was evaluated in the CSF of 50 patients with non-tuberculous neurological diseases (control group). The results obtained with this antigen were compared with commercially available tuberculin purified protein derivative (PPD2) and BCG antigens. PPD2 gave false negative results (50%) in culture positive patients with TBM, and BCG antigen gave false positive results in 32% of non-tuberculous subjects. PPD1 gave a sensitivity of 60% in culture negative patients with TBM and no false positive reactions in the non-tuberculous group. PPD1 antigen, in contrast to other mycobacterial antigens, can be very easily prepared in any routine laboratory, and this antigen is recommended for use as an aid in the laboratory diagnosis of TBM, particularly in culture negative patients with TBM.

Antibodies, Bacterial↗
PubMed1991

Rapid diagnosis of tuberculous meningitis with a dot enzyme immunoassay to detect antibody in cerebrospinal fluid.

A simple dot enzyme immunoassay (Dot-EIA) was carried out to detect antibody to Mycobacterium tuberculosis antigen 5 in cerebrospinal fluid (CSF) specimens from 40 patients with a clinical diagnosis of tuberculous meningitis (TBM). The assay gave a positive reaction in all ten patients with culture proven TBM. In 30 culture negative patients with TBM, the assay was positive at a titre of 1:16 in 18 patients. In 40 patients with non-tuberculous neurological diseases (control group) the assay was negative at a titre of 1:16. The Dot-EIA had an overall sensitivity of 70% and a specificity of 100% in the diagnosis of TBM. This assay could be used as a rapid screening test to establish the diagnosis of TBM, particularly in patients in whom bacteriological investigations for Mycobacterium tuberculosis in CSF specimens are negative.

Adolescent↗
PubMed1991

Detection of Mycobacterium tuberculosis antigen 5 in cerebrospinal fluid by inhibition ELISA and its diagnostic potential in tuberculous meningitis.

Inhibition ELISA was used to quantitate Mycobacterium tuberculosis antigen 5 in cerebrospinal fluid (CSF) specimens of 40 patients with a clinical diagnosis of tuberculous meningitis. In all 10 culture-proven patients, the assay was positive; in 30 culture-negative patients, the assay yielded positive results for 21. CSF antigen 5 concentrations ranged from 9 to 82 ng/ml (mean +/- SD, 45.5 +/- 6.2). In 40 patients with nontuberculous neurologic diseases, mean concentration was 1.45 ng/ml. Thus, inhibition ELISA for the detection of M. tuberculosis antigen 5 in CSF has definite diagnostic potential during the active phase of the disease and should be a routine diagnostic test, particularly when bacteriologic cultures in CSF are negative for M. tuberculosis.

Adolescent↗
PubMed1991

A dot-immunobinding assay for the laboratory diagnosis of tuberculous meningitis and its comparison with enzyme-linked immunosorbent assay.

In an attempt to establish an alternative to standard bacteriological methods in the laboratory diagnosis of tuberculous meningitis (TBM), a simple dot-immunobinding assay (Dot-Iba) was standardized to detect Mycobacterium tuberculosis antigen 5 and antimycobacterial antibody in cerebrospinal fluid (CSF) specimens of patients with TBM. Sensitivity and specificity of Dot-Iba was compared with conventional enzyme-linked immunosorbent assay (ELISA) and standard bacteriological techniques. The Dot-Iba showed excellent correlation with indirect ELISA for the detection of antimycobacterial antibody in CSF and showed 60% sensitivity and 100% specificity in culture-negative patients with TBM. However Dot-Iba was less sensitive for the detection of antigen 5 in CSFs and showed false negative results (60%) in culture-positive patients with TBM.

Antibodies, Bacterial↗
PubMed1991

Immunohistochemical demonstration of mycobacterial antigens in intracranial tuberculoma.

Mycobacterial antigens have been demonstrated immunohistochemically in the paraffin sections of 10 intracranial tuberculous granulomas and the results were compared with the detection of acid fast bacilli by conventional Ziehl-Neelsen method. In none of the 10 specimens, acid fast bacilli were demonstrated while mycobacterial antigens were characterised as diffusely staining granular brownish-pink material within the cytoplasm of giant cells and macrophages. In 14 specimens of granulomatous lesions due to non-tuberculous aetiology, immunohistochemical stains were negative for mycobacterial antigen. Thus demonstration of mycobacterial antigen will be not only useful in establishing mycobacterial aetiology of a caseating intracranial granuloma but also can be used as an alternative method to the conventional Ziehl-Neelsen method.

Antigens, Bacterial↗
PubMed1991

Correlation between culture of Mycobacterium tuberculosis and antimycobacterial antibody in lumbar, ventricular and cisternal cerebrospinal fluids of patients with tuberculous meningitis.

In this study positive culture for M. tuberculosis were obtained, 20% in lumbar cerebrospinal fluid (CSF), 75% in ventricular CSF and 87.5% in cisternal CSFs of patients with tuberculous meningitis. Low culture positivity in lumbar CSF is due to the low density of circulating tubercle bacilli in lumbar CSF than in cisternal or ventricular CSFs. However antimycobacterial antibody in lumbar, cisternal and ventricular CSFs circulate in significant titres and are not statistically different from one another. Since specimens of CSF can not be obtained from cisternal or ventricular routes for the routine bacteriological investigations in patients with tuberculous meningitis, detection of antimycobacterial antibody of M. tuberculosis antigen 5 in lumbar CSF by an indirect ELISA may be considered as an aid for the diagnosis of tuberculous meningitis, particularly when repeated CSF cultures are negative for M. tuberculosis.

Antibodies, Bacterial↗
PubMed1991

Circulating immune complexes in cerebrospinal fluid of patients with tuberculous meningitis.

Circulating immune complexes (ICs) were isolated from cerebrospinal fluids (CSFs) of patients with tuberculous meningitis (TBM), non-tuberculous neurological diseases by a polyethylene glycol (PEG) precipitation method. Mycobacterium tuberculosis antigen 5 was detected in CICs of 30% patients with TBM, by sandwich ELISA. CIC level decreases during antituberculosis chemotherapy and therefore its detection can provide a method to monitor the therapeutic schedule in patients with TBM.

Adolescent↗
PubMed1991

Intracranial cystic meningioma.

Two cases of intracranial cystic meningiomas are reported. Neuroradiological and intraoperative diagnoses in both cases were cystic astrocytoma. However routine biopsy during the intra-operative period and an accurate interpretation during frozen-section will establish the diagnosis of cystic meningioma. Complete excision of cyst wall of the meningioma during the surgery will minimise the incidence of recurrence of these benign tumours.

Adult↗
PubMed1991

Hydrolysed microspheres from cross-linked polymethyl methacrylate (Hydrogel). A new embolic material for interventional neuroradiology.

Highly hydrophilic, perfectly smooth and spherical microspheres have been synthetized. These non-biodegradable microspheres absorb water in varying degrees and can be injected easily through microcatheters due to their slippery and compressible characteristics. The material was successfully used for embolization of 4 vascular intracranial tumours and 2 spinal vascular lesions in the cervical region, by superselective delivery. Histopathology confirmed absolute inertness of the microspheres.

Adult↗
PubMed1991

Potential application of dot-immunobinding assay as a rapid diagnostic test in tuberculous meningitis.

A simple dot-immunobinding assay (Dot-Iba) in nitrocellulose paper was developed for the detection of specific IgG antibody to Mycobacterium tuberculosis antigen 5 and mycobacterial antigen in cerebrospinal fluid of patients with tuberculous meningitis (TBM). The assay gave 77.1% sensitivity for the detection of IgG antibody to M. tuberculosis antigen 5 and 48.6% sensitivity for the detection of mycobacterial antigen in patients with TBM.

Adolescent↗
PubMed1991

Rapid serodiagnostic test for pulmonary tuberculosis.

Immune complexes (ICs) were isolated from sera of patients with pulmonary tuberculosis (PT), non-tuberculous pulmonary diseases and healthy control subjects by polyethylene glycol (PEG) precipitation method. Specific mycobacterial antibody in ICs was tested against an affinity purified mycobacterial antigen by counter-current immunoelectrophoresis (CIE). The results show that specific mycobacterial antibodies are present only in ICs of patients with PT (70%). Therefore CIE could be used as a simple and rapid serodiagnostic test in patients with PT, particularly when bacteriological methods in sputum specimens are negative for Mycobacterium tuberculosis. CIE has several operational advantages over ELISA and best suited to laboratories with limited resources.

Counterimmunoelectrophoresis↗
PubMed1990

Diagnosis of tuberculous meningitis by enzyme-linked immunosorbent assay to detect mycobacterial antigen and antibody in cerebrospinal fluid.

Enzymed-linked immunosorbent assay (ELISA) was used to detect mycobacterial antigen and antimycobacterial antibody in cerebrospinal fluid (CSF) specimens of 50 patients with tuberculous meningitis (TBM) and 50 patients with non-tuberculous neurological diseases (control group). The assay gave no false negative results in 10 culture-positive patients with TBM. Detection of mycobacterial antigen in CSF is more sensitive and specific for the diagnosis of TBM than detection of antibody, ELISA should be considered as one of the alternative methods in the laboratory diagnosis of TBM, particularly in culture-negative patients with TBM.

Antibodies, Bacterial↗
PubMed1990

Detection of mycobacterial antigen in cerebrospinal fluid: diagnostic and prognostic significance.

Inhibition enzyme-linked immunosorbent assay (ELISA) was standardised to quantitate circulating mycobacterial antigens in cerebrospinal fluid (CSF) specimens. Of the 40 patients with clinical diagnosis of tuberculous meningitis, the assay was found to be positive in 26 patients. In a control group of 42 patients with non-tuberculous neurological diseases the assay was negative. The assay showed a sensitivity of 65 and 100% specificity for tuberculous meningitis. In 8 patients with tuberculous meningitis receiving chemotherapy, multiple CSF examinations were subjected to this assay. The antigen concentration showed a gradual decrease between 3 and 4 weeks after the commencement of antituberculosis chemotherapy. There was a positive correlation between clinical recovery and antigen concentration. Detection of mycobacterial antigen in CSF specimen by inhibition ELISA has not only diagnostic utility but also could be applied to monitor antituberculosis chemotherapy in patients with tuberculous meningitis. The assay is reproducible and feasible for routine immunology laboratory. It also could be considered as a diagnostic aid when repeated bacteriological cultures are negative in CSF specimens of patients with tuberculous meningitis.

Antigens, Bacterial↗